Transcript Nervous System

REGULATION
Nervous System
The nervous system maintains homeostasis
by controlling and regulating all other parts
of the body.
Functions of the Nervous System
1. Sensory-uses receptors to gather
information from all over the body
2. Interpretation-the brain then processes
the information into possible responses
3. Response-sends messages back through
the system of nerve cells to control
body parts
Evolutionary Trends of the Nervous System
Complex
Simple
Animal
Taxon
Type of
Nervous
Tissue
Aquatic
Invertebrates
Flatworms &
Roundworms
Segmented
Worms &
Arthropods
Vertebrates
A simple system with
interconnected neurons
called nerve nets;
contain specialized cells
for touch and chemical
detection
Ganglia (a group of
nerve cells) and nerve
cords run along the
body; can detect
chemicals, touch, and
some have eyespots
Cephalization occurs
which is the
concentration of nerve
cells in a head region to
form a brain; intense
senses in arthropods
A well developed
brain evolved from
the spinal cord; the
size and complexity
increases from fish to
mammals
Picture of
system
planaria, flukes,
Examples
sponges, jellyfish
tapeworm,
hookworm
earthworm, ants,
grasshopper, bees
mammals, birds,
reptiles, fish,
amphibians
Structures of the Nervous System
Neurons: the functional cell that transmits signals
through the body; an individual nerve cell
Parts of a Neuron
1. cell body- the largest part of the neuron; contains
the nucleus and organelles
2. dendrites- short, branching extensions spreading
out from the cell body; receive and carry impulses
to the cell body
3. axon- long, fibrous part of neuron; conducts
nerve impulses away from cell body
4. at the end of the axon, the impulse travels across
the synapse, a tiny gap separating the axon of one
neuron from the dendrite of another. Once the
impulse reaches the end of the axon, it is able to
jump the gap by changing into a neurotransmitter.
Neuron
Nerve Impulse- an electrical signal is sent from the dendrite, along
the axon, to the terminal. A chemical message, called a
neurotransmitter is released from the axon terminals into the
synapse, where it travels to the next cell.
Types of Neurons
a. sensory neuronscarry impulses from
sense organs to brain
b. motor neuronscarry impulses from
brain/spinal cord to
muscles/organs
c. interneurons- carry
impulses between
sensory and motor
neurons
Divisions of the Nervous
System
• Central
Nervous
System
(CNS)
• Peripheral
Nervous
System
(PNS)
Central Nervous System (CNS)
A. Brain- “control center”- receives and
analyzes information; processes and
sends back instructions
Parts of the Brain
1. Cerebrum
controls thought, language, learning,
judgment, & voluntary action
2. Cerebellum
controls involuntary functions of muscles &
maintains balance and posture
3. Brain stem (Pons & Medulla Oblongata)
Controls involuntary functions such as
breathing, heart rate, and swallowing
4. Thalamus, Hypothalamus
Controls homeostasis- temperature, hunger,
thirst, flight or flight responses
Spinal cord- link between the brain
and PNS; also controls reflexes
Reflex: a simple, automatic
response (ex. Hand on a tack)
Peripheral Nervous System
(PNS)
A. Consists of
nerves- ropelike
bundles of
neurons
B. Gathers
information,
delivers it to and
from CNS
Levels of Organization
Neurons
Nerves
Brain
Nervous
Interaction with other systems for Regulation
 Bones of the skeletal system protect
the spinal cord and brain.
 The brain controls heart rate, blood
pressure, and breathing via the
circulatory and respiratory systems.
 Glands in the brain control the release
of hormones of the endocrine and
reproductive systems.
 The brain controls muscles both in
digestion and movement.
Diseases / Disorders of the
Nervous System
1.
Polio- a virus that attacks the spinal cord; eventually
causes paralysis
2. Multiple Sclerosis (MS)- affects neurons; slows nerve
impulses, causing muscle weakness, possibly paralysis.
3. Alzheimer’s- brain tissue deteriorates; severe memory
loss
4. Stroke- a blockage in a blood vessel in the brain,
causing brain damage
5. Concussion- a bruise to the brain when the brain hits
the inside of the skull
Fun Facts
A human body contains more nerve
cells than there are stars in the Milky Way
Neurons are the largest cell in the body
and do NOT undergo mitosis
Nerve impulses move at 100 meters
per second or more
Longest axon of a neuron is 15 ft! (in
the giraffe)